Expanded web of sheet material and method of making same

Abstract

A composite expanded web for making a cigarette wrapper is provided, the web comprising a laminate of a first web of generally flat sheet material and a second web of expanded sheet material. The expanded web is formed by passing a web of sheet material through rotary shearing and forming dies to impart to the web a configuration having longitudinally disposed rows of generally sinusoidal convolutions extending above and below the original plane of the web, each row of convolutions lying 180° out of phase from its abutting rows. The composite web is formed into a wrapper for a smoking article by curling it about its longitudinal axis, securing the overlapping edges of the first web with a glue seam, and cutting it to the desired length.

I claim: 
     
       1. A method of making an expanded composite web, comprising: a. providing a first web of formable sheet material;   b. shearing and forming the first web in a plurality of rows across its width to form convolutions extending longitudinally along the web, each convolution extending above and below the original plane of the web in a generally sinusoidal configuration and joined to the next convolution by a web portion lying substantially in the original plane of the web; and   c. laminating a surface of the sheared and formed first web to a surface of a second web of sheet material.   
     
     
       2. The method of claim 1 in which the periodicity of the generally sinusoidal convolutions is adjustable. 
     
     
       3. The method of claim 1 or claim 2 in which the web of formable sheet material comprises a sheet material about 3 mils thick. 
     
     
       4. The method of claim 3 in which the web of formable sheet material comprises a cellulosic material. 
     
     
       5. The method of claim 1 in which the second web is cigarette paper. 
     
     
       6. The method of claim 1 or claim 2 in which the width of the web of formable sheet material is substantially an even multiple of a desired cigarette wrapper circumference. 
     
     
       7. The method of claim 1 in which the width of the second web is sufficiently greater than that of the first web to provide an overlap seam upon curling the composite web about its longitudinal axis to form a tube. 
     
     
       8. The method of claim 1 or claim 2 in which each row of convolutions extending longitudinally along the web lies 180° out of phase from its abutting rows. 
     
     
       9. A method of making an expanded web, comprising providing a web of formable sheet material and imparting to the web a configuration of rows of generally sinusoidal convolutions extending longitudinally along the web, each convolution extending above and below the original plane of the web and joined to the next longitudinally succeeding convolution by flat portion of the web lying substantially in the original plane of the web. 
     
     
       10. The method of claim 1 or claim 2 in which the upper and lower extremities of the generally sinusoidal convolutions are generally flat and lie substantially parallel to the original plane of the web of formable sheet material. 
     
     
       11. A composite web, comprising a lamination of first and second webs of sheet material, the first web further comprising expanded sheet material having a plurality of rows of generally sinusoidal convolutions sheared and formed longitudinally along the web and the rows extending across the web width, each convolution extending above and below the original plane of the first web and connected to each successive convolution by a portion of the first web lying substantially in the original plane of the first web. 
     
     
       12. The composite web of claim 11 in which the periodicity of the generally sinusoidal convolutions is adjustable to regulate gas flow along the longitudinal axis of the web. 
     
     
       13. The composite web of claim 11 in which the extremities of the convolutions are generally flat and lie substantially parallel to the original plane of the first web. 
     
     
       14. The composite web of claim 11 in which the first web comprises a sheet material about 3 mils thick. 
     
     
       15. The composite web of claim 14 in which the sheet material comprises a cellulosic material. 
     
     
       16. The composite web of claim 11 in which the second web comprises cigarette paper. 
     
     
       17. The composite web of claim 11 in which the width of the first web is an even multiple of a desired cigarette wrapper circumference. 
     
     
       18. The composite web of claim 11 in which the width of the second web is sufficiently greater than the width of the first web to provide an overlap seam upon curling the composite web about its longitudinal axis to form a tube. 
     
     
       19. The composite web of claim 11 in which each row of convolutions lies 180° out of phase from its abutting rows.